Step 1: Concept
A relation $R$ on set $A$ is reflexive if $(a, a) \in R$ for every $a \in A$.
Step 2: Meaning
The set $A$ contains elements $\{4, 5, 7, 8, 9\}$.
Step 3: Analysis
Checking for reflexivity: $(4,4), (5,5), (7,7), (8,8),$ and $(9,9)$ are all present in $R$.
Step 4: Conclusion
Since all identity pairs for set $A$ exist in $R$, the relation is reflexive.
Final Answer: (C)